Yarn
Yarn is a long continuous length of interlocked fibres, used in sewing, crocheting, knitting, weaving, embroidery, ropemaking, and the production of textiles. Thread is a type of yarn intended for sewing by hand or machine. Modern manufactured sewing threads may be finished with wax or other lubricants to withstand the stresses involved in sewing. Embroidery threads are yarns specifically designed for needlework. Yarn can be made of a number of natural or synthetic materials, and comes in a variety of colors and thicknesses. Although yarn may be dyed different colours, most yarns are solid coloured with a uniform hue.
Etymology
The word "yarn" comes from Middle English, from the Old English gearn, akin to Old High German garn, "yarn", Dutch garen, Ancient Greek χορδή, and Sanskrit, "band". It originally referred to entrails.History
The human production of yarn is known to have existed since the Stone Age. Fiber materials came from animal hides, reeds, cotton, wool, and silk. Textile trade contributed immensely to the ancient global economy.Materials
Yarn can be made from a number of natural or synthetic fibers, or a blend of natural and synthetic fibers.Natural fibers
Cotton
The most common plant fiber is cotton, which is typically spun into fine yarn for mechanical weaving or knitting into cloth.Silk
is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by the larvae of the moth Bombyx mori. Silk production is thought to have begun in China and silk thread and cloth manufacture was well-established by the Shang dynasty.Linen
is another natural fiber with a long history of use for yarn and textiles. Linen fibers are derived from the flax plant.Other plant fibers
Other plant fibers which can be spun include bamboo, hemp, maize, nettle, and soy fiber.Animal fibers
The most common spun animal fiber is wool harvested from sheep. As long fibers make better yarn, sheep have been bred over time to produce longer fibers. This increases the need for shearing to prevent pests and overheating.Other animal fibers used include alpaca, angora, mohair, llama, cashmere, and silk. More rarely, yarn may be spun from camel, yak, possum, musk ox, vicuña, cat, dog, wolf, rabbit, bison, or chinchilla hair, as well as turkey or ostrich feathers.
Synthetic fibers
Some examples of synthetic fibers that are used as yarn are nylon, acrylic fiber, rayon, and polyester. Synthetic fibers are generally extruded in continuous strands of gel-state materials. These strands are drawn, annealed, and cured to obtain properties desirable for later processing.Synthetic fibers come in three basic forms: staple, tow, and filament. Staple is cut fibers, generally sold in lengths up to 120 mm. Tow is a continuous "rope" of fibers consisting of many filaments loosely joined side-to-side. Filament is a continuous strand consisting of anything from one filament to many. Synthetic fiber is most often measured in a weight per linear measurement basis, along with cut length. Denier and Dtex are the most common weight to length measures. Cut-length only applies to staple fiber.
Filament extrusion is sometimes referred to as "spinning," but most people equate spinning with spun yarn production.
Yarn from recycled materials
yarn is a recycled yarn made from the same fabric as is used in T-shirts and other clothes. It is often made from the remainder fabric of clothing manufacture, and therefore is considered a recycled and eco-friendly product. It can also be made at home out of used clothing. The resulting yarn can be used in knitted or crocheted items.Comparison of material properties
In general, natural fibers tend to require more careful handling than synthetics because they can shrink, felt, stain, shed, fade, stretch, wrinkle, or be eaten by moths more readily, unless special treatments such as mercerization or super washing are performed to strengthen, fix color, or otherwise enhance the fiber's own properties.Some types of protein yarns may feel irritating to some people, causing contact dermatitis, hives, or wheezing. These reactions are likely a sensitivity to thicker and coarser fiber diameter or fiber ends. In fact, contrary to popular belief, wool allergies are practically unknown. According to a study reviewing the evidence of wool as an allergen conducted by Acta Dermato-Venereologica, contemporary superfine or ultrafine Merino wool with their reduced fibre diameters do not provoke itch, are well tolerated and in fact benefit eczema management. Further studies suggest that known allergens applied during textile processing are minimally present in wool garments today given current industry practices and are unlikely to lead to allergic reactions.
When natural hair-type fibers are burned, they tend to singe and have a smell of burnt hair; this is because many, like human hair, are protein-derived. Cotton and viscose yarns burn as a wick. Synthetic yarns generally tend to melt, though some synthetics are inherently flame-retardant. Noting how an unidentified fiber strand burns and smells can assist in determining if it is natural or synthetic, and what the fiber content is.
Both synthetic and natural yarns can pill. Pilling is a function of fiber content, spinning method, twist, contiguous staple length, and fabric construction. Single ply yarns or using fibers like merino wool are known to pill more due to the fact that in the former, the single ply is not tight enough to securely retain all the fibers under abrasion, and the merino wool's short staple length allows the ends of the fibers to pop out of the twist more easily.
Yarns combining synthetic and natural fibers inherit the properties of each parent, according to the proportional composition. Synthetics are added to lower cost, increase durability, add unusual color or visual effects, provide machine washability and stain resistance, reduce heat retention, or lighten garment weight.
Structure
Spun yarn
Spun yarn is made by twisting staple fibres together to make a cohesive thread, or "single". Twisting fibres into yarn in the process called spinning can be dated back to the Upper Paleolithic, and yarn spinning was one of the first processes to be industrialized. Spun yarns are produced by placing a series of individual fibres or filaments together to form a continuous assembly of overlapping fibres, usually bound together by twist. Spun yarns may contain a single type of fibre, or be a blend of various types. Combining synthetic fibres with natural fibres is very common. The most widely used blends are cotton-polyester and wool-acrylic fibre blends. Blends of different natural fibres are common too, especially with more expensive fibres such as alpaca, angora and cashmere.Yarn is selected for different textiles based on the characteristics of the yarn fibres, such as warmth, light weight, durability, or softness.
Yarn is composed of twisted strands of fiber, which are known as plies when grouped together. These strands of yarn are twisted together in the opposite direction to make a thicker yarn. Depending on the direction of this final twist, the yarn will have either s-twist or z-twist. For a single ply yarn, the direction of the final twist is the same as its original twist. The twist direction of yarn can affect the final properties of the fabric, and combined use of the two twist directions can nullify skewing in knitted fabric.
The mechanical integrity of yarn is derived from frictional contacts between its composing fibers. The science behind this was first studied by Galileo.